This part of GB/T 4909 specifies the test equipment, test piece preparation, measurement procedure, test results and evaluation of the reverse bend test in the bend test of bare wires. This part is applicable to the determination of reverse bend performance of the round-section conductors such as copper, aluminum and its alloys, bimetallic wires and so on which have a nominal diameter d of 0.3 mm ~ 10.0 mm as well as the specially-shaped section conductors with characteristic size less than 20.0 mm (such as contact wires).